Before Al Gore became vegan, People for the Ethical Treatment of Animals (PETA) protesters said he could not really be an environmentalist unless he became a vegetarian. Photograph: Jay Directo/AFP/Getty Images

Putting our money behind our personal convictions helped to bring down South Africa’s apartheid regime. But when does joining a consumer boycott of products or services produced by a specific company or originating in a given region of the world make sense?

It’s a question that seems to arise more and more frequently, involving a growing number of products. Even before the latest flareup of fighting in Gaza, some friends chastised others for buying Israeli-grown fruit and Pink Floyd rocker Roger Waters slammed Scarlett Johansson for appearing in ads for SodaStream, which makes its carbonation devices on the West Bank. (The storm of criticism cost Johansson her role as a humanitarian ambassador for Oxfam.)

I watched as the “boycott or not” debate over the Olympics (and, secondarily, over vodka) divided friends in the months leading up to this year's Sochi Winter Games. The majority were protesting against Russia’s draconian anti-LGBT laws, but a handful were equally exercised over the roundup and euthanasia of stray dogs in Sochi in order to make the streets look more orderly to visitors. Others found other reasons to advocate boycotts. Political figures, from President Barack Obama to Chancellor Angela Merkel, stayed away; the athletes attended. Those sports fans who felt strongly about it went to the movies instead.

Activists holding placards depicting President Vladimir Putin, participate at a protest against Russia's law on gays. Photograph: Lefteris Pitarakis/AP

And as for the vodka ban? Well, despite all the furore – including vodka being poured on to the streets by bar owners – beverage industry analysts say the actual impact on sales had been easing, as some clubs called an end to the boycott earlier this year. That was until Russia occupied Crimea, when some liquor stores began pulling Russian vodka off their shelves in protest and entirely new groups started to advocate boycotting.

In fact, everywhere you look, it seems there are pleas to boycott an ever-growing number of companies and products. If you support reproductive rights, there’s an argument in favour of not directing your consumer dollars to Hobby Lobby, which just won supreme court approval for not providing insurance coverage for some types of birth control for its employees. That also may mean you should stop buying any of Eden Foods’ soy milk or organic pasta: that company does not want to provide any birth control.

If you’re concerned about working conditions in the garment industry in Bangladesh, you will probably be boycotting a lot of the “fast fashion” industry – and many garments made in Bangladesh, Cambodia and other countries just in case. Don’t fly Air France if you’re an animal-rights supporter: they transport research animals to laboratories. Your holiday plans shouldn’t include Japan, China, Botswana, Mauritius or even Canada (the seal hunt … )

Driving a Volvo or shopping at Victoria’s Secret, to some, means supporting Israel at the expense of Palestinians.

As this very small list of boycott opportunities shows, there are myriad ways to use your purchasing power in hopes of swaying the behaviour of a corporation or even national policies.

But will it work?

It can. It has done. Just think of the 18th-century English boycott of sugar, and the role it played in the eventual abolition of slavery. Or the part that a popular boycott of tea played in the American revolution. Modern-day boycotts of companies that continued doing business in Burma contributed to decisions to pull out of the country and led to the demise of the military junta there.

For instance, for all its aggressive campaigning, People for the Ethical Treatment of Animals (Peta) hasn't succeeded in getting us to give up eating meat and dairy products, wearing leather and wool, or taking our children to circuses. It has transformed popular attitudes to fur and to the testing of cosmetics and other beauty products, and helped spawn other groups that emphasise humane treatment of farm and laboratory animals. That’s not what Peta supporters want, but it may be what many animal lovers are happy to support.

If you want your consumer dollars to make change, here are some points to bear in mind.

Be focused

If you’re opposed to Israel’s occupation of the West Bank, boycotting Caterpillar and Volvo – which make vehicles that have been used to demolish Palestinian homes in the West Bank – may be absolutely logical. But sales to Israel are a small fraction of their overall business, and sales of vehicles used for that purpose an even smaller fraction. Volvo isn’t marketing its bulldozers for that purpose, meaning that you’ll have an uphill battle.

An easier task? Focusing on homegrown businesses, whether sales of Israeli produce or yes, even SodaStream. (But be prepared with answers for the Palestinian workers employed at the SodaStream plant as to why you want their livelihood to vanish – they’re opposed to a boycott.)

After appearing in ads for SodaStream, Scarlett Johansonn stepped down from her role as Oxfam ambassador. Photograph: Rex

Pick a big issue – and choose your target carefully

The bigger the issue, and the easier it is for folks to become outraged about it, the more participants you’ll have and thus the more dollars are involved. If you’re an activist, you’ll always be passionate – but you need to recognize that most of the rest of the world is preoccupied with more mundane stuff and is readily distracted, especially if they are hearing the same arguments repeatedly, as in the minimum-wage debate. The best targets are those whose reputations are already waning, say academics who have studied the matter: it makes it easier for other consumers to follow your lead and just walk away.

Be vigilant and attentive

If you’re going to boycott, you need to be hyper-aware of your consumer decisions. If you eat in a restaurant, where does that food come from? Was it ethically sourced and is it organic? Where was that inexpensive T-shirt made? Ethical Consumer compiles a list of currently active boycotts, and provides information about how to support “good” companies as well as shun “bad” ones.

Be patient

It took decades to do away with the slave trade and to end apartheid. Boycotts are only one of the tools that are helping to change attitudes to animal rights and workers’ rights – and they may not always be the most effective. Some boycotts may feel particularly futile: for everyone who boycotts SodaStream, someone else may deliberately purchase one of their carbonated beverage devices simply because that consumer wants to support Israel. For the foreseeable future, it may have to be enough to know that your consumer dollars, at least, aren’t going to a company whose business practices you disapprove of.